What is a Baker's cyst?

Question

She had a bypass operation and is on warfarin, suffers from polymyalgia rheumatica, and is on steroids and blood pressure medication.

She also had a mastectomy 18 years ago – there has been no recurrence of cancer.

She has been going to a physiotherapist in Australia for treatment of her back injury from a fall and polymyalgia rheumatica.

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The physiotherapist said that mum may have a Baker's cyst behind her knee.

What is a Baker's cyst?

Answer

It must be a worry to you that your mother is living so far away and suffers from a number of different ailments.

A Baker's cyst is a firm, walnut-sized fluid-filled lump behind the knee.

In conditions like rheumatoid arthritis, to which polymyalgia rheumatica (PMR) is closely related, there is an increased pressure within the fluid inside the knee joint which leads to a ballooning in a backwards direction of the synovial membrane which lines the knee joint.

Most of the time, Baker's cysts are relatively painless and some may even clear up spontaneously within a few months.

Usually however, the cyst will persist and may even rupture, causing fluid to leak down between the layers of the muscles in the calf.

When a cyst ruptures there will certainly be some pain and swelling.

Diagnosis can be confirmed using arthrography where an injection of a radio-opaque substance is given, allowing the joint space to be viewed clearly on X-ray.

Treatment generally consists of a supportive bandage, although in some instances surgical removal of the cyst may be required.

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